Bandsaw book trimmer

ABSTRACT

The book bindery system includes a trimming machine, a rounding and backing machine and a casing-in and backing-in machine. When operating each machine accommodates different sizes of books. The trimming machine consists of three band saws having cutting runs disposed normal to the direction of advance of books thereby. The saws are positioned to trim selvage from the two side edges and the top edge opposite the spine of each book. Means are provided for serving changes in the size of books and for adjusting the positions of two side cutting saws as well as the top cutting saws so that the amount of selvage removed from the three edges remains the same whatever size the book may be. The rounding and backing machine consists of a plurality of rounding wheels spaced apart from a plate which has an elongated depression formed therein along which the spines of the books run. The plate is heated to soften adhesive at the spine and the rounding wheels serve to both round the pages of each book and to force the spine into the depression and thereby to shape it. A plurality of backing rollers are rotatably mounted downstream of the heated plate to further shape the spine. The casing-in and building-in machine is composed of a pair of spaced apart conveyor chains having horizontal runs parallel to the direction of advance of the books. A plurality of horizontally disposed rods are resiliently mounted along the lengths of the chains and the rods serve to engage books of varying thicknesses and to advance them to a station. At the station each book in turn is deposited on a cover and the rods serve to advance the books and covers past an adhesive activating station thence between a pair of spaced formers which serve to fold the cover into contact with the front and back pages of the books. Pressure is applied to bond the covers to the books and points are indented in proximity to the spines.

Stroud, deceased et a1.

1 1 BANDSAW BOOK TRIMMER [75] Inventors: William Felix Stroud. deceased. late of McKellar. Canada; by Lois Evelyn Stroud. executrix. McKcllar, Canada. Edward John Stroud. McKcllar, Canada 173] Assigncc: Stroud Graphic Equipment Limited,

McKell-ar. Ontario, Canada [221 Filed: Dec. 26, 1972 [2l| Appl. No: 318,617

1521 US. Cl. 83/368; 83/404; 83/422; 83/4252; 83/428183/433; 83/661,83/806; 83/925 A {51} Int. Cl 326d [/52 [58] Field of Search 83/368, 404, 422. 425.2. 83/428, 433, 806, 925 A, 661. 407, 4

1561 References Cited UNITED STATES PATENTS 363,461 5/1887 Hatfield 83/4 X 1,123,412 1/1915 Smith 83/806 1.131297 3/1915 Lewis... 83/368 2,064,261 12/1936 Howe et a1... 83/661 2,822,003 2/1958 McC'ahon et a1, 83/404 X 2,852,052 9/1958 Hansen. 83/661 3,072.158 1/1963 Duarte...... 83/806 X 3,073,197 1/1963 (iowin 83/368 3,393,538 7/1968 Mercier 83/4 X 3,51 1,122 5/1970 Sherrill et a1 83/422 X 3,554,247 1/1971 Larsen 83/368 X Primary Examiner-Frank T. Yost Attorney, Agent, or Firm 1ames '11 Wilbur; Frank 1. Piper; Arne 1. Fors [57] ABSTRACT The book bindery system includes a trimming mai 1 June 10, 1975 chine, a rounding and backing machine and a casingin and backinga'n machine. When operating each machine accommodates different sizes of books. The trimming machine consists of three band saws having cutting runs disposed normal to the direction of ad vance of books thereby. The saws are positioned to trim selvage from the two side edges and the top edge opposite the spine of each book, Means are provided for serving changes in the size of books and for adjusting the positions of two side cutting saws as well as the top cutting saws so that the amount of selvage removed from the three edges remains the same whatever size the book may be. The rounding and backing machine consists of a plurality of rounding wheels spaced apart from a plate which has an elongated de pression formed therein along which the spines of the books run, The plate is heated to soften adhesive at the spine and the rounding wheels serve to both round the pages of each book and to force the spine into the depression and thereby to shape it. A plurality of backing rollers are rotatably mounted downstream of the heated plate to further shape the spine. The casing-in and building-in machine is composed of a pair of spaced apart conveyor chains having horizontal runs parallel to the direction of advance of the books. A plurality of horizontally disposed rods are resiliently mounted along the lengths of the chains and the rods serve to engage books of varying thicknesses and to advance them to a station. At the station each book in turn is deposited on a cover and the rods serve to advance the books and covers past an adhesive activating station thence between a pair of spaced formers which serve to fold the cover into contact with the front and back pages of the books. Pressure is applied to bond the covers to the books and points are indented in proximity to the spines.

4 Claims, 25 Drawing Figures SHEET PATENTEDJUH 10 ms PATENTEDJUH 10 ms 3.888; 150

IHHHIMH PATENTEDJUN I 0 1915 3.2518: .150

BANDS/N BOOK TRIMMER This invention relates to an integrated hook bindery system and also relates to certain indhidual constitu tent elements of such sy stcm.

Known hook bindery systems comprise a number of different machines for carrying out the various steps of the binding operation. 'lhe system may include a hot melt binding machine. a trimmer. a rounding and backing apparatus and a machine for applying hard covers to hound pages (a casingilf machine). Generaily. such machines function entirely independent of one another and when operating are designed to handle one specific size and kind of book. whether paperback or hard on er. Fach machine must be set up for the spe' cific size of book passing through the system and if a different size of book is to be produced. then the system must be shut down to permit appropriate adjust ments to he made to each individual machine.

It would of course be desirable to bring all of the ma chines together so as to provide an automated binding system where loose sheets or signatures of the book could be collated and fed in at one end of the system and wherein the finished cased-in book could emerge at the other end. Howe\er. if the various known ma chines are put together in succession. the system would still suffer from the disadvantage mentioned above. namely that the whole system when operating would handle only one size and kind of book and the system would have to be shut down to permit adjustment of each individual machine ofthe system to accommodate differing kinds and sizes of hooks to he produced there from.

It is a broad object of the present invention to pro vide an integrated book bindery system which will function efficiently in the formation of either paper back or hard cover books from collated sheets or signatures and which will function when in operation to accommodate different sizes of collated sheets to produce different sizes of hooks without the necessity of shutting down the system and individually adjusting each of the constituent machines.

Another object of the invention is to provide improved component machines of the bindery system including a book trimmer. a rounding and backing apparatus and a casing-in apparatus. These machines may. if desired. be utilized independently of one another along with other bindery machines of known type.

A further and more specific object is to provide a continuous flow non-indexing machine for trimming books. the machine being capable while operating of adjusting itself to whatever size hook is fed therein.

A still further object is to provide a rounding and hacking apparatus self-adjusting while in operation and suitable for use not only with books consisting of sections or signature? but by hooks bound by the so called "perfect binding" method. "Perfect binding is a term used in the trade for the binding of single pages into a hook by gluing along the spine as opposed to books consisting of signatures which are sewn together. Perfect binding was developed as an economical method of binding paperback books and one method has been to glue the books at the spine with a hot melt adhesive. Hot melt is a plastic which is applied a few degrees above its melting point and which then cools rapidly. permitting the almost instantaneous handling of the books. Until fairly recently. perfect binding was used for paperbacks only whilst the hard cover books were made up from sewn signatures.

In hard cover books, the spine is rounded and hacked and various attempts have been made to date to incorporate the perfect binding technique into the binding of hard cover hooks utilizing cold resin adhesives or animal glue. However. this would involve piling the freshly glued books onto skids for several hours whilst they dry. the books then being put through the tradi tional rounding and backing machines which were designed to handle the sewn signature type of binding.

Attempts to round and back books glued with hot melts with the usual rounding and backing machines have failed because if the spine is formed after the hot melt has cooled. the spine will resume its original flat shape in a few days because of the quality identified as memory in the plastic. The subject rounding and backing apparatus may be utilized to handle books wherein the spine can retain its rounded shape during the rounding and backing steps which are carried out whilst the plastic adhesive is hot; the adhesive subsequently being cooled down into the desired configuration of the spine.

A still further object is to provide a casing'in and building-in apparatus which need not be set up for dif ferent sizes and thicknesses of books. the apparatus adjusting automatically to books of different sizes and thicknesses while in operation, and instantaneously bonding the cases to the books thereby allowing immediate handling upon completion thereof.

The invention is explained with reference to the accompanying drawing in which:

FIG. I is a layout of the integrated book bindery system. partly diagrammatic and partly in simplified plan;

FIG. 2 is a perspective view of the trimming saws in the trimmer section of the machine;

FIG. 2A is an elevation of a portion of the band saws illustrated in FIG. 2;

FIG. 2B is a section on line 2B 2B of FIG. 2A;

FIG. 3 is a detailed perspective view ofautomatic lateral adjustment means for one of the trimmer saws;

FIG. 4 is an elevation. partly in section showing the automatic vertical adjustment mechanism for one of the trim saws;

FIG. 5 is a perspective view of the rounding and backing apparatus;

FIGS. 6, 6A, 6B, 6C and 6D are enlarged elevations of backing rollers which are or may be employed in the apparatus of FIG. 5;

FIG. 7 is a plan view of the apparatus illustrated in FIG. 5;

FIGS. 8 and 9 are sections in enlarged scale on lines 88 and 99 respectively of FIG. 7;

FIG. I0 is a perspective view of a modified form of the rounding and backing apparatus illustrated in FIG.

FIG. II is a section on line II-I1 of FIG. I0;

FIG. I2 is an elevation. partly simplified of the easing-in and building-in apparatus;

FIG. 13 is a plane view ofthe upstream portion of the casing-in and building-in apparatus;

FIG. 14 is a perspective view of the upstream end of the casing-in and building-in apparatus;

FIG. 15 is a partial enlarged perspective view of a portion of the apparatus shown in FIG. 14;

FIG. 16 is a perspective view downstream of the view shown in FIG. I4.

FIG. 17 is a plan view of guide means illustrated in FIG. 16:

FIG. 18 is a perspective view of the downstream end of the casing-in and building-in apparatus; and

FIG. I) is a section on line I9 of FIG. 18;

Like reference characters refer to like parts throughout the description of the drawings.

THE INTEGRATED BINDERY SYSTEM The integrated bindery system of the invention is designed to accept books which have been printed and collated and perform all the bindery operations needed to make a finished book. By way of clarification. it should be noted at this point that the term book is utilized throughout the specification to refer to the arti cle in all its stages through the bindery system from the collated books aforesaid to the finished cased-in books with hard covers.

The integrated bindery machine of the invention utilizes a sequential arrangement of hot melt binder, trimmer, rounder and backer and casing-in and buildingin apparatus, all arranged to function automatically and to be self-adjusting whereby various types and sizes of collated books may be fed initially into the hot melt binder without having to close the whole integrated machine down for the adjustment of the other elements of the machine. In the machine described herein, the hot melt binder is of conventional construction whilst the trimmer, the rounder and backer and the casing-in and building-in apparatus all constitute novel individual constituent elements of the machine in their own right.

Referring now to FIG. 1 ofthe drawings, the printed and collated books B enter the machine at 20 and pass into a hot melt binder 21 which, as mentioned hereinbefore, is of conventional form in the subject machine. In the hot melt binder 2], the spine of the books B may be ground in the usual manner and, at this stage, if the books are to be paperbacks and not cased-in hard cover books, the cover is applied thereto at 21a. If the books are to be cased-in, a stretch cloth may be applied instead of the cover or, alternatively, wrap-around end papers consisting of a single sheet or two folded sheets joined with stretch cloth may be applied.

The books now designated Bl leave the hot melt binder 21 in a lapped formation, as shown by reference numeral 22 and are then fed to the trimming apparatus generally 23 on conveyor belt 24. Horizontally travelling conveyor belts 25a and 25h carry the books along in stacked formation to bandsaw 43 in the trimmer section of the bindery machine. A backup block 24a may be required to force a given number of books into contact with the band saws. The band saws trim the books on the top side while the glued spine rests on the conveyor belt 24. The books then pass onto a table 26 and to band saws 34, 36 where the two side edges of each book are trimmed.

After this trimming stage, the books, now identified as 8-2, pass over a heated portion of table 26 which perheats the spine to soften the hot melt adhesive pre paratory to the book BZ entering the rounding and backing apparatus 27. As shown in FIG. I, the books B2 are unstacked from the trimmer section by conveyor belts I56 and 158 and conveyed serially through the rounding and backing apparatus 27; the final operation of which may be made to include the application of head and tail bands as at 28. The final stage in this system comprises a cover feed 29 and a casing-in and building-in apparatus designated 30, from whence the completed book is delivered ready for packing in up propriate cartons or like means. It should also be noted that in FIG. I the system may be utilized for the hot melt binding and trimming of paperback books which do not of course pass through a rounding and backing apparatus 27 or a casingdn and building-in apparatus 30, an alternative take-off conveyor 31 being provided downstream of the trimmer section 23 for taking off such trimmed paperback books.

THE SELF-ADJUSTING BOOK TRIMMER The trimmer illustrated in FIGS. 2 and 4 is a continuous flow nonindexing machine for trimming books. The machine is capable of adjusting itself to whatever size book is fed into it and need not be shut down when books of one size are changed for books of another.

With reference to FIG. 2. books 8-] are shown in a stacked formation with their glued spines 32 resting at the upstream side on the horizontally travelling con veyor belt 24 and on the downstream side on table 26. A pair of spaced apart vertically cutting band saws 34, 36 serve to trim the two side edges of the books. Band saws 34 is trained about upper and lower rollers 3811. b respectively, while band saw 36 is trained about upper roller 40a and a lower roller, not illustrated. Rollers 384:, h are positioned rotatably on a housing (not illustrated) which is mounted upon movable trimming station or bed 41 (FIGS. 1 and 3) while rollers 40a are also positioned on a housing and mounted to an immovable trimming station or bed 42 (FIG. I). A horizontally cutting band saw 43 serves to trim the upper edge of the books and the saw is trained about spaced rollers 44a, I) rotatably mounted to a movable trimming station or housing (described below) and driven by conventional means, not illustrated. It will be noted that the directions of the cutting runs of the band saws 34, 36, 43, where they contact the pages. indicated by arrows 34a, 36a and 43a, are parallel to the planes of the pages and normal to their direction of advance through the trimmer.

The cutting edges of the band saws, illustrated in FIG. 2A and indicated generally 46 are defined by a plurality of teeth each composed of a leading edge 48 which is oriented at an oblique angle to the direction of travel of the blade, indicated by double headed arrow 50, and a trailing edge 52 which is oriented generally horizontally to the direction of travel. With reference to FIG. 2B, the face of each tooth which contacts the edges of the trimmed pages, indicated 54 has no set," i.e. the edge is coplanar with the remainder of the non-cutting surface of the blade in contact with the trimmed pages indicated 56. The oppositely facing surface 58 of each tooth which contacts the trimmed material or selvage 60 (FIG. 2) from each page is beveled and meets face 54 at a sharp edge.

The tooth construction of the band saws 34, 36, 43 permits smooth trimming of any desired width of selvage 60 from the pages constituting books B- l. The sel vage material may be carried away by appropriate vacuum means such as a suction hood (not illustrated l.

FIG. 3 illustrates the upstream end of book advance belt 250: (also shown in FIG. I which presses laterally against the side edges of books 8-1 to advance them to the book trimming band saws illustrated in FIG. 2. Belt 25a is trained about vertically disposed rollers 60, 62

journalled in hearings in bed 41 and a similarly mounted roller rm (Fl(i. I] at the downstream end maintains the belt taut and in contact with the page edges Any one of the rollers is connected to a convcntional prime mover (not illustrated) to drive the belt horizontally in the direction of arrow ()8.

The side edges of the books are also contacted by a sensor 70 in the form of an elongated rectangular strip bent outward of the direction of hook advance at its up stream end at 71 to prevent its jamming the books as they travel thereby. A pair of spaced parallel rods 72, 74 extend normally from the face of the sensor not in contact with the book side edges and the rods are slide ably received in a pair of spaced apertures 76, 73 formed in a rigid support post 80 carried by bed 41. A plate 82 interconnects the ends of rods 72, 74 opposite sensor 70. Suitable resilient means such as coil compression spring 84, 86 bias the sensor into contact with the side edges of the books at all times.

Plate 82 carries a central electrically insulated termi nal 88 of a micro-switch assembly further constituted by opposed electrically insulated terminals 90. 92 which extend upwardly from base 94 mounted to sup port post 80. The micro-switch is in circuit with an electric motor 95.

Bed 41 is mounted in tracks or other suitable means (not illustrated) for slideable horizontal movement in a direction normal to the direction of travel of the books. The direction of movement of bed 41 is indicated by arrow 96. The bed is provided with a block 98 having a threaded opening for receipt of a threaded worm shaft 100 driven by motor 95. Rotation of the shaft will cause the bed to move either toward or away from the books depending on whether the shaft rotates clockwise or counter-clockwise.

Sensor 70 together with the aforementioned parts operatively connected thereto serve to position band saw 34 correctly to remove the same width of selvage from the side of books B-l whatever size the books may be within a given range of sizes. Such positioning is accomplished continuously; there is no necessity to halt the passage of books for an extended period in order to permit repositioning of the band saw where the size of books passing by the saw changes, The means by which repositioning of the band saw takes place is as follows: When the size of pages of books passing by sensor 70 increases. the pages will press laterally against the sensor causing it to move outwardly i.e. toward support post 80. Outward movement of the sensor will thus cause central terminal 88 to complete an electrical circuit through terminal 90 thereby causing motor 95 to rotate shaft 100 in a direction necessary to move bed 41 outwardly away from the stream of books. As the bed moves horizontally outwardly so too will belt a and band saw 34. both trained about rollers which move horizontally with the bed. As long as the books keep pressing against sensor 70, the electrical connection between terminals 88. 90 will be maintained and bed 41 will continue to move outwardly. When the bed has moved sufficiently far that the side edges of the books no longer overcome the bias of springs 84, 86, terminal 88 will move away from terminal 90 and motor 95 will shut off Conversely when the size of books passing by sensor 70 decreases. springs 84. 86 bias the sensor inwardly into contact with the smaller books thereby causing central terminal 88 to make electrical connection with (ill terminal 92. Motor thereupon causes shaft to rotate in a direction necessary to move bed 41 inwardly and the bed will continue to move until the booktacing surfaces of sensor 70 and belt 251: are coplanar at which time the micro-switch assembly opens,

The opposing belt assembly 25b (F10. 1) and the band saw 36 are trained about rollers which are rotatably mounted to a fixed bed 42. The belt 25b and saw 36 are accordingly not horizontally adjustable either inwardly or outwardly and when the size of books ad vanccd by belt 25b changes. movable bed 41 will con tinue to move inwardly or outwardly until the space be tween the two belt assemblies 25a. 25b equals the width of the stream of books.

FIG. 4 illustrates the means by which the position of the horizontally cutting band saw 43 is adjusted to books of various sizes within a given range. The adjusting means illustrated therein. indicated generally 107. is similar to that illustrated in FIG, 3. With reference to FIG. 4. sensor 108 contacts the top edges 109 of the books and is connected by means of spaced rods 110, 1 12 to atop bar 114. A housing is mounted to the top bar 114 and a thumb screw 116 is rotatably mounted in an opening in the housing 115 and is threadably received in a bracket 117 to which a pair of spaced parallel electrically insulated terminals 118. 1 19 are mounted in circuit with an electric motor (not illustrated).

A central electrically insulated terminal 122 disposed between terminals 118. 119 is connected to a band saw housing 124 movable upwardly and downwardly in the direction of arrow 126 by means of a worm shaft 128 driven by the last-mentioned electric motor. Rollers 440. b are journalled in bearings provided in the housing.

Rods 110, 112 are slideably mounted within openings in a bracket 130 fixed to housing 124 and a pair of compression springs 132, 134 mounted about the rods beneath the bracket bias sensor 108 into contact with the books.

As with sensor 70, the location of sensor 108 either upwardly or downwardly determines the location of the top trimming saw 43. When for example. central terminal 122 is contacted by upper terminal 118, the electric motor rotates shaft 128 to cause saw 43 and bracket 130 to move downwardly.

Adjustment of the amount of the trimmed off the book or the width of selvage is obtained by appropriate rotation of thumb screw 116. 1f more trim is required, the screw is turned to move upper terminal 118 closer to central terminal 122 and conversely ifless trim is required. lower terminal 119 is moved closer to the cen tral terminal by means of the thumb screwv Where books passing through the trimming assembly are to be attached to hard covers. i.e. where the books are of the cased-in type. it is preferable to substitute for the adjusting means 107 illustrated in FIG. 4 an adjusting means at the delivery end ofthe hot melt binder 21. The adjusting means is shown diagrammatically in FIG. 1 and comprises a sensor and microswitch assembly 141 both similar to that described with reference to HO. 3. The sensor 140 however determines the thickness of each book as it passes thereby while the books are in an end to end position and before they become lapped as at 22.

Variations in the thickness of the books are detected by micro-switch 141 which is electrically connected to the motor which adjusts the height of top band saw 43. However. by means of a suitable memory means 142 such as an IBM I800 Data Acquisition and Control System or an IBM System/7 Sensor Based System these variations are not reflected in the position of the top band saw until the books are beneath the saw.

By means of the just described adjusting means. the thickness of each book will govern the vs idth of selvage removed from the top of the pages by top band saw 43. The thicker the book. the more selvage will be removed by the saw and the shorter will be the height (spine to upper edge) of the book (shown as 143 in FIG. 2). Conversely. the thinner the book. the higher the saw will be and the greater the height 143 will be. Provided that the "cases" or covers in which the books are mounted are of uniform dimensions. the square" or the distance between the two side edges of the finished book and the side edges of the case or cover. indicated I44 in FIG. I8, will be uniform.

With further reference to FIG. I. disposed immediately downstream of belt advance rollers 66, 67 is a pair of elongated guides I52, I54 respectively. each being flared outwardly at the upstream end and being spaced apart a distance equal to the width of the hooks downstream. Guides I52, I54 are mounted to beds 41, 42 respectively such that the space between them adjusts to the size of books passing therebetwcen. The guides extend vertically upwardly from the beds sufficiently to contact a substantial portion of the side edges of the pages thcrebetween.

Guides 152, I54 serve to straighten any books which may be improperly aligned and not at right angles to the direction of travel of belt 24. The guides operate as follows: if a book is misaligned on the belt such that one side reaches guide I52 before the other side reaches guide I54. the former side will no longer be pushed by belt 25a whereas the latter side will continue to be pushed forward by belt 25b. The guides also ensure that books are packed tightly together before passing between saw 34, 36 since the tightly packed books will provide necessary back-up support for books being trimmed.

Up to this point. the spines 32 of the books have been resting on the lower moving conveyor belt 24 but when the books pass between guides I52 154, the spines move onto table 26. The table facilitates the packing process since side belts 2511.17. and bottom belt 24 all co-operate to press the books tightly between guides 152, 154 while table 26 provides the necessary friction for the spine of the book which is being pushed onto the table by lower belt 24.

THE ROUNDING AND BACKING APPARATUS After the trimming operation, the books now identitied as 8-2 in FIG. I pass over table 26 which preheats the spine to soften the hot melt adhesive. The books are then unstacked by conveyor belts I56. 158 and are conveyed serially through rounding and backing appa ratus 27.

With reference to FIG. 5, books 1-3-2, spine side down, are moved through the rounding and backing apparatus in the direction of arrow 158 by means of a pair of spaced horizontal conveyor chains generally 160 and MI (FIG. 7) which contact the front and back pages respectively of each book. A pair of spaced rails I62. I63 (FIG. extend parallel to the direction of advance of the books above chain 160 and like rails are disposed above chain lt'il. Iiach pair of rails contact the outer pages on opposite sides of each book and the rail pairs are interconnected by a plurality of pivoted members 164 which permit selective horizontal posi tioning of one rail relative to the other. The purpose of the rails is to support the upper part of the books as they are being rounded or backed.

Each book upon entering the rounding and backing apparatus first passes over first station comprising a heated plate 163 having a flat upper surface I66. The book then passes over a second heated plate I68 at a second station. Plate I68 is provided with a concave longitudinal depression or channel formed in its upper surface. Disposed above plate I68 is a rounding wheel I72 rotatably mounted to a pair of spaced brackets I73u,h and having its LttiS disposed normal to the direction of advance of the book. Wheel I72 is posi tioned such that its rim presses the upper edges of the pages downwardly. The hot melt adhesive in the spine of the book being softened to a ductile state by the heated plate yields to permit the spine to conform to the shape of channel 170.

Each book then passes over spaced backing rollers I74. I76, 178 at a third station, The backing rollers are provided with concave depressions on their outer sur faces and a second wheel ISO is optionally disposed above a book which is riding upon the rollers to force the top edges of pages of the book and its spine into concave and convex configurations as illustrated. Wheel I80 may be freely rotatably mounted to brackets 1730.1: and its axis as well as the axes of rollers I74. I76. I78 are normal to the direction of book advance.

Mounted upstream of rounding wheel 172 is an adjusting means indicated generally I81. The adjusting means is of the same construction as adjusting means 107 illustrated in FIG. 4 and also serves to sense the position of the top edges of books passing thereby. Brackets 173a,!) are connected to means IS! in the same way as saw housing 124 is attached to adjusting means I07 such that a change in the size of books passing by adjusting means 181 produces a corresponding change in the position of wheels I72, I80.

Books passing by rollers I74. I76, I78 pass onto a cooling plate 182 also provided on its upper surface with a concave channel I84 conforming in shape to the spine of the book passing thereover. The cooling plate serves to set the adhesive which has been previously softened by means of heated plates I65, I68 as well as by table 26.

The horizontal book advance conveyor chains I60, l6l are illustrated in detail in FIG. 7 and cross sections thereof are shown in FIGS. 8 and 9. Books 8-2 are sandwiched between the two chains and are moved thereby in the direction of the arrows. The chains I60. l6l being the same. one only will be described. Chain I60 is trained about a pair of sprocket wheels I86, I88 positioned at the upstream and downstream ends re spectively of the rounding and backing apparatus and the sprockets are driven by suitable means (not illustrated). The chain is composed of two sets of spaced links 190, a interconnected by pins 191 about which enlarged freely rotatable rollers I92. 19211 are positioned. A pressure member 194 is also mounted about each pin 19].

Each pressure member has a rounded bookengaging face 196 and is freely pivotal with respect to the chain such that the member does not grip the book when it first comes into contact with it. as seen at position 200 (FIG. 7 Thc pressure member does not exert its full pressure until its avis is in alignment with a line joining the axes of sprockets I86. I87 lthc line being marked 202 in FIG. 7) or until the rollers I92 beside the pressure member made full contact with the pressure plate 204 described below. A \cry light spring-backing or other means may be used to prevent the pressure menu her from swinging into an unwanted position while travelling in that portion of its circuit which does not bring it into contact with a hook.

Pressure plate. generally 204. is in two parts and is disposed on opposite sides ofthe books at the upstream side of their passage through the apparatus where the rounding operation occurs. The pressure plate is composed of two parallel spaced membcrs 206, 208. A plu rality of spaced pairs of rods 20') FIG. 8 extend from the innermost member 206 and the rods are slideably recen ed in apertures formed in the other member. Resilient means such as a compression spring 210 is positioned about each rod and biases the members 206, 208 into a spaced apart relationship. The outermost member 208 is anchored while the inner member 206 is held in position only by springs 2H) and rods 209 so that the latter member is biased inwardly.

Inner member 206 contacts rollers 192, I921: and exerts a light inward force thereto to cause pressure menv hers I94 to grip the books lightly while the rounding wheels I72. press the pages downward into the concave channel 170. Since the books are gripped only lightly. the rounding wheel 172 can easily form the upper edges ofthe pages into the desired rounded shape. FIG. 8 shows a cross section of the book and apparatus at this point and it is to be noted that the hook is indented only slightly by pressure members I94.

A second pair of pressure plates 220 is disposed on opposite sides of the books as they pass over the backing rollers I74, I76, I78. Unlike pressure plate 204 however, pressure plate 220 is not spring loaded but is anchored in position and exerts greater pressure on the chain rollers I92, I921: to cause pressure members 194 to grip the books very firmly as the books are being "backed" by the backing rollers. FIG. 9 shows a cross section ofthe book and apparatus at the point at which the backing operation is taking place and it will be ob served that the lower portion of the book adjacent the spine is flared out by the rollers while held by pressure members I94.

The relative positions of pressure plates 204, 220 may be adjusted centinuously to accommodate books of varying thickness. The means by which such adjust ment is achieved is similar to the way in which the horirontal position of band saw 43 is adjusted by sensor I40. micro-switch assembly and memory means I42 and a detailed description thereof is believed unncces sary. By means of the adjusting means. together with adjusting means I81. the rounding and backing appara tus will have a self-adjusting feature similar to that of the book trimming apparatus With reference to FIGS. 6. 6A and 6B. backing rollers I74. I76 and I78 taper toward their centres from a shallow taper at I74 at the upstream end to a more acute taper at I78 at the downstream end. There may be more than three backing rollers in which case the difference in taper bctw cen successive rollers will be more gradual.

Rollers I74. I76, I78 may be substituted by or complemented with rollers of different orientations and shapes such as are illustrated in FIGS. 6C. 6D. With reference first to FIG. 6C. the illustrated roller 230 has a beveled peripheral surface which tapers in cross section from one end to the other. A number of grooves 23] oriented parallel to the roller axis are spaced about the peripheral surface. The axis of roller 230 may be oriented at any suitable angle including angles oblique both to the direction of travel of books 8-2 as well as to the plane of the pages of books passing the rcby. The orientation of the roller will be that appropriate to the degree ofbacking" desired. Roller 230 would be used in conjunction with another like roller, one roller on each side of a book passing thereby. A number of pairs of such rollers may also, of course, be used.

FIG. 6D illustrates a roller 232 tapering in cross section from the two ends to the centre thereof. A helix 234 is formed in the peripheral surface of the roller and a suitable prime mover may be employed to rotate the roller in the direction of travel of the books and at a rate that its peripheral surface travels slightly faster than the rate of book advance. The helix will accordingly create an outward pressure on the surface of the book spine thereby causing the pages to move to the peripheral edges of the books. The hand of the helix of the roller may be opposite to that shown in which case the roller will be driven more slowly or in the opposite direction in order to create the outward pressure necessary to effect the backing operation.

It should be noted that the sequence of operations carried out by the apparatus illustrated in FIG. 5 may be reversed. That is to say. in FIG. 5 rounding occurs before backing. This is the preferred sequence however it is possible to perform the backing operation before rounding.

Wheels 172 and 180 may be solid and non-adjustable or may be adjustable. With reference to FIG. 9, wheel 180 is composed of resilient material such as rubber and is contacted at each side by circular plates 236, 238. A threaded shaft 240 passes through an axial opening in the wheel and the ends of the shaft are journailed in bearings of brackets I73a,b. Nuts 246. 248 are threadably mounted to the shaft and the nuts are disposed on opposite sides of the wheel. Tightening of the nuts against plates 236, 238 will cause the plates to press closer together with resulting compression of the resilient material and increase in the curvature of the rim of the wheel. Conversely slackening of the nuts will result in a decrease in the curvature of the wheel.

The curvature of the wheel rim can therefore be altered to accommodate books of different thicknesses. It will be understood of course. that any one or all of the rounding wheels can be constructed in the manner described.

FIGS. 10 and 1] illustrate a rounding apparatus which may be used in place of the rounding apparatus illustrated in FIG. 5 and may be disposed upstream or downstream of the backing apparatus. Books B-2 in FIG. 10 move first over a heated plate 250 having a flat upper surface. then over a second heated plate 252 having a longitudinal concave depression in its upper surface. Rounding wheels 254. 256 are disposed above the books.

Books 8-2 are spaced apart and between a pair of endless chains 258, 260. The chains are driven in the direction of arrow 262 by suitable sprocket wheels (not illustrated) and as shown the chains each have a reach parallel to the direction of book advance. A plurality of spaced rods 264 interconnect the chains and successive rods are spaced apart sufficiently to accommodate a book therebetween. The rods engage the trailing edges of the books and serve to advance the books through the apparatusv Optionally chain conveyors I60, 16] may also be used to facilitate shaping of the spines running along the depression in plate 252.

An endless belt is disposed above and below each chain 258, 260. The belts above and below chain 258 are indicated 266, 267 in the drawing. As shown. the belts run in a direction parallel to the direction of ad vance of the books and are trained about rollers. one for each belt 266, 267 being illustrated and indicated 268. 269 respectively. Suitable means is provided for driving the rollers.

Rigidly mounted between the forward and return reaches of each belt 266, 267 are pressure plates 270, 272 which are anchored in position by suitable means (not illustrated) and which serve to press the inner reach of each belt into contact with the books. The belts therefore serve to maintain the books in an upright position.

AUTOMATIC CASING-IN AND BUILDING-IN APPARATUS FIG. 12 illustrates the casing-in apparatus somewhat schematically. The apparatus serves to apply hard covers to books passing from the rounding and backing operation. With reference to FIG. 12 books now identitied 8-3 are delivered on conveyor belt 280 from the rounding and backing apparatus 27 to the main con veyor of the casing-in apparatus. The main conveyor indicated generally 282 drives the books along support plate 283 (FIG. 12). Wheels 283 and rails 3830 similar to wheels 172 and rails 162 respectively may optionally be employed to maintain the spines of the books in contact with plate 283 and to prevent the books from buckling.

The construction of the main conveyor is shown in detail in FIGS. 13, 14, and 15. The conveyor consists of two parallel link chains 284, 286 disposed on opposite sides of the books. Chain 284 is trained about sprocket wheels 288, 290 disposed upstream and downstream respectively of the apparatus. The lower and upper reaches of chain 284 are disposed parallel to the direction of travel of books through the apparatus and the chain is driven by suitable means (not illustrated such that its lower reach travels in the direction of book travel (indicated by arrow 292). Chain 286 moves in like manner.

A conveyor rod 294 is slideably mounted in each segment of chains 284 286. The rods are disposed horizontally and normal to the chains and to the direction of travel of the books. With particular reference to FIG. 15, each rod is freely slideably and rotatably received in an aperture formed in a link segment 296 FIG. 15 and has one end 298 adapted to contact the side wall of a book and another end fitted with a cap 300. A register arm 301 extends normally from the rod approximately midway between the link segment 296 and rod end 298. Resilient means such as a tension spring 302 disposed about the rod between the link segment and the cap. biases the rod into contact with a book unless the rod is restrained by the interaction of the cap 300 and guide 304 (described in more detail below). Spring 302 also maintains the arm in vertical position unless the arm contacts one of shelves 305 (FIG. 14). A detent 306 is fastened to rod 294 and is accommodated within a conforming recess 307 in link segment 296 when spring 302 is not retained by guide 304. The detent maintains the register arm 30] in a ver tical position.

Two shelves 305 are provided. each being horizontally disposed and being spaced outwardly from each of the two side walls of the books. The shelves are dis posed at a somewhat higher elevation than the book spines and are supported in position by suitable means (not illustrated).

A pair of spaced apart guides 304. 3040 commence in proximity to the upper portion of sprocket wheel 288 at point 304!) in FIG. 12. The guides are spaced apart along their lengths from a respective one of link chains 284. 286. The spacing between the guides varies from a minimum at the ends 3041:, 304c to a maximum approximately midway of their ends.

The operation of main conveyor 282 is described with reference to FIGS. 13 and 14. Books 133 are moved in the direction of arrows 292 by conveyor belt 280 FIG. 12 to a position at which conveyor rods 294 would normally be biased into engagement with the books. At the upstream end of main conveyor 282 however. the rods are prevented from doing so by the interaction of their respective caps 300 with guides 304. The guides at each side of the com eyor however angle inwardly at their downstream ends toward the books whereby the rods 294 can move inwardly into engagement with the books as they travel in timed relation to the books. Thus no matter what the thickness of books 5-3, the conveyor rods will engage and support them.

Conveyor rods 294 disposed beside spaces between successive books will be biased inwardly until they touch one another as shown by rods identified as 294a in FIGS. 13 and 14. In this position. the rods 294a per form two functions. First the rods push books 13-3 along support plate 283 FIGv 12 and secondly, their register arms, marked 301a FIGS. 14 and 15 which are verti cally disposed in the space between the books and shelves 305 (and maintained in such position by the interaction of detent 306 and recess 307) serve to engage a cover as explained below. The register arms on those rods 294 which contact the books (and which do not contact one another) are maintained at a higher elevation than the book spines by shelves 305.

With further reference to FIG. 12, a plurality of hard covers C are stacked on conveyor belt 310 disposed horizontally below support plate 283. and the covers are held in an upright position at the upstream end of the belt by an appropriate block 312. Belt 310 feeds the covers to an upwardly inclined conveyor belt 314 which runs at slightly greater surface speed than belt 310. The interaction of the two belts 310 314 together with a convention feed control mechanism 316 resting on top of the covers causes the covers to stack in a somewhat pyramid shaped pile against upwardly inclined suction belt 318. The space between mechanism 316 and the facing surface of belt 318 is large enough to permit the passage of only one cover C at a time.

The covers C are carried upward in turn by suction belt 318 and are deposited on the upper surface of a third upwardly inclined conveyor belt 320 which delivers the covers to the upper surface of a horizontally disposed conveyor belt 322 which upper surface s generally coplanar with the upper surface ol support plate 283.

Each book in turn in conveyed to con\c \or belt 322 by contacting rods 294a upstream of the book. With reference to FIG. 12, the leading edge 324 of a book which is about to contact belt 322 is timed to be slightly behind the leading edge 326 of the cover also about to contact belt 322. The book will therefore be above the cover C on belt 322. Main conveyor 282 is timed to run slightly faster than conveyor belt 322 thus the book overtakes the cover. The cover will be advanced initially by both belts 320 and 322 then by aforesaid register arms h: when the cover is entirely on belt 322. The arms place the cover into proper register with the book so that the cover overlaps the upstream and downstream end of the book an equal distance.

As indicated, the correct end-twend positioning of the book 8-3 on the cover C is achieved by means of downwardly depending register arms 3011:. Correct side-to-side positioning of the book on the cover is achieved by means of guides 326, 328 mounted in proximity to the downstream end of main conveyor 282. The guides 326. 328 are shown schematically in FIG. l2 and in more detail in FIGS. 16 and 17. As shown. guide 326 is composed of an upstream portion 32611. which angles inwardly at an oblique angle to the direction of book travel and connects with the downstream portion 326!) which is parallel to the direction of travel. Guide 328 is the mirror image of guide 326. Guides 326, 328 are fastened at the lower edges and beneath the upper reach of conveyor belt 322 FIG. 12 to block 330, 332 FIG. 17 respectively. journaled to bushings allowing them to slide back and forth freely on rods 334, 336 respectively. mounted by suitable means normal to the direction of book travel. Arm 338, 340 are pivotally connected at one end to blocks 330, 332 respectively and the other ends of the arms are pivotally connected to a respective end of a central swinging arm 342 to which tension is applied by appropriate resilient means in the direction ofarrow 344 such as to bias guides 326, 328 inwardly. The central axis 346 of arm 342 is mounted directly beneath the centre of the track of books B-3.

It will be understood that guides 326, 328 always move in unison and are always an equal distance from the centre of the track of books. The guides, being biased inward into contact with the side edges of the cov ers C. ensure that the covers will be centred in a sideto-side relationship with the books.

With reference to FIG. 16, attachment of the covers C to the books according to the instant apparatus may be accomplished by means of an adhesive applied ei ther to the inside upper surface 348 of the covers or to the front and back pages 350, of the books. The adhesive is applied beforehand by suitable means (not shown) and is allowed to dry before the books reach the casing-in and building-in apparatus. Suitable adhesives include those which can be reactivated by heat and those which can be reactiulted by a solvent. Examples of the former adhesives are those made from polyvinyl acetate polymeric resin and from polyethylene and parafin was. FIG. 16 illustrates means by which a solvent may be applied to reactivate an adhesive applied either to surfaces 348 or 350. 35L

With reference to FIG. 16, supply vessels 352, 354 are fastened to the outside wall of guides 326, 328 respectiwly. Perforated tubes 356, 358 are slideably connected to the vessels and the tubes pass through openings in the guide walls and terminate in enlarged feet (one only illustrated and marked 360). Suitable resil ient means mounted for example in vessels 352, 354 urge feet into contact with opposite sides of the book and the upstream ends of the feet are inclined outwardly so that they may be separated by books passing thereby. In such manner the length of perforated tubes 356, 358 are always adjusted to the width of the cover C since the self-adjusting guides 326, 328 and the book thickness will govern the length of tube which extends out of the supply vessels.

Solvent is fed to vessels 352, 354 by a suitable central source and the liquid is sprayed onto the upper inside wall 348 of the cover as shown.

If the adhesive applied to the cover or the books is reactivated by heat, the reactivating apparatus may be the same that shown in FIG. 16 except that hot air instead of solvent flows from perforated tubes 356, 358. The self-adjusting feature of the tubes would not be affected by such a change.

Disposed downstream of perforated tubes 356, 358 are spaced formers 362, 364, positioned on opposite sides of books passing therebetween. The books are carried downstream of conveyor 282 by means of a pair of spaced conveyor chains. one being illustrated and marked 265. These chains are described below. The upstream end 362a of former 362 is generally horizontal and coplanar with the upper surface of conveyor belt 322 FIG. 12. Downstream of end 3620. the outer edge of the former inclines gradually inwardly and upwardly to its downstream end 362b (FIG. I8) which is disposed vertically above belt 322. Former 364 is the mirror image of former 362. As the books and covers pass between the formers 362, 364, the covers are raised from a horizontal position to the vertical position shown in FIG. 18.

The covered book now designated B4 in FIG. 18 passes between spaced guides 364, 366 which are of the same structure as guides 326, 328 and are resiliently biased inward by the same means as are guides 326, 328 such that the outer walls of book B-4 contact the facing inner walls of guides 364, 366.

Guides 364, 366 function to adjust the relative positions of pressure roller assemblies generally 368, 370 by means ofa micro-switch assembly generally 372 associated with one guide. As shown, assembly 372 is composed ofa terminal 374 disposed between a pair of parallel terminals 376, 378 connected to the base 380 of pressure roller assembly 368. Assembly 368 is movable normal to the direction of book advance by means of rollers 382, 384 which are mounted to the lower surface of the base and which ride in guide tracks 386, 388 respectively. Assembly 370 is similarly movable. A motor 390 rotates a worm shaft 391 provided with two sets of threads of opposite hand. one set 392 being threadably received in apertures in base 380 while the other set 394 being received in the base 396 of assembly 370 for adjusting the realtive positions of the assemblies.

The micro-switch assembly 372 operates in the same manner as the assembly shown in FIG. 3 for maintaining the relative positions of the pressure roller assemblies so that they will apply the same inward pressure to books passing thcrebetween whatever the thickness of the books may be. For example and with reference to FIGS. I8 and I9, if guide 364 carrying contact 374 moves outward then electrical connection will be made with terminal 378 completing the circuit to activate the motor 390 to revolve shaft'39l such that pressure belt assemblies 368, 370 move apart.

Pressure roller assembly 368 is composed of a pair of rollers 400, 402 journaled on shafts rotatably mounted in base 380 and top plate 404. A pressure belt 406 is trained about the rollers and may be faced with some resilient material such as foam rubber or plastic. Alternatively. the belt may take the form of spring-loaded pads in belt form. The belt is driven by suitable means (not illustrated). Pressure belt assembly 370 is of the same construction as the just-described assembly 368.

Pressure belt assemblies 368. 370 are for the purpose of pressing the solvent coated or heated covers C against the book outer walls to ensure complete bonding of the covers to the books and thus to complete the casing-in operation. It should be noted that where a heat softenable adhesive is used the adhesive may be softened by heat applied by the pressure belts. ln such event the adhesive may be heated by heated plates. ul trasonic devices or other suitable means. Where the rollers are heated as indicated the perforated tubes 356, 358 and apparatus associated therewith may be dispensed with.

The means by which the building-in operation is accomplished is explained with reference to FIG. 12. The operation serves to form an indentation or "joint along the front and back surfaces of the cover parallel to and in proximity to the spine. With reference to FIG. 12, a pair of spaced coveyor chains (one illustrated and marked 265) are disposed on opposite sides of books B3. The chains have parallel book advancing runs which are disposed parallel to the direction of advance of the books and which commence approximately at the upstream end of formers 326, 328 and terminate at pressure assemblies 368, 370. A pair of spaced rails 402 is spaced above each roller and contact the oppositely facing cover walls and a plurality of wheels 404 having their axes oriented normal to the direction of book advance are disposed above the pressure plates. Chains 265 and rails 402 have the same construction as chains 160, 161 and rails 162, 163 (FIG. 7) and wheels 404 have the same construction as rounding wheels 172 (FIG. 5).

The pressure members of chains 26S (equivalent to member 194, FIG. 7) are urged into contact with the books by pressure plates of the same construction as pressure plates 220 (FIG. 7). Pressure members contact books at the same place as do members 194 shown in FIGS. 8 and 9. The pressure plates however exert a considerable inward force on the books in order to cause pressure members to form a pronounced indentation or joint into the covers. The position of the pressure plates may be adjusted to the thickness of books passing between chains 400 in the same way as may plates 220.

Where the covers are attached by means of a heat softenable adhesive, pressure members may be heated to a temperature sufficient to maintain the adhesive in a softened condition. In such event it may be advisable to provide means to cool rapidly the covers about the joint and cooling rods 408 may be used for the purpose. Rods 408 are disposed downstream of chains 265 and are aligned with pressure members in the operating runs of the chains. The chains push the books between the rods such that the rods are disposed in the joints.

The rods being cooled serve to harden the adhesive in proximity to the joint and securely fasten the covers to the books.

It will be understood of course that modifications can be made in the preferetl embodiments of the intention described and illustrated herein without departing from the scope and purview of the appended claims.

We claim:

1. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for advancing said books downstream to said trimming sta tion; trimming means mounted on said trimming station and such that the edge from which the selvage is removed is opposite a spine of said book; a sensor mounted upstream ofsaid trimming means and adapted to be resiliently biased into contact with one of said front page and said back page such that a change in the thickness of a book contacted by said sensor produces a corresponding change in the position of said sensor; and means operatively connected to said sensor and to said trimming means for detecting changes in the position of said sensor and for causing a resulting change in the position of said trimming means when said book is trimmed thereby so that the width of selvage rcmoved by said trimming means varies directly with the thickness of the book.

2. The machine as claimed in claim 1 wherein said detecting means comprises: a micro switch constituted by a post mounted upstream of said trimming station; a first electrical terminal slideably mounted to said post and being normally spaced apart from and between a pair of spaced apart second and third electrically insu latcd terminals fixed to said post. said sensor being connected to and slideable with said first terminal such that a change of position of said sensor produces a corre sponding movement of said first terminal into electrical contact with one of said pair of terminals; said machine further including memory means in circuit with said electrical terminals and with a prime mover for moving said trimming station; said memory means storing responses to book changes detected by said sensor and activating said prime mover to reflect said responses whereby the position of said trimming means is adjusted according to the thickness of book trimmed thereby.

3. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for ad vancing said books downstream to said trimming sta tion; trimming means mounted on said trimming station and positioned to remove selvage from an edge oppo site a spine of each book; a sensor mounted to contact one of a front and back page of each said book such that a change in the thickness of a book contacted by said sensor produces a corresponding change in the position of said sensor; and means operatively connected to said sensor and to said trimming means for detecting changes in the position of said sensor and for causing a resulting change in the position of said trimming means when said book is trimmed thereby so that the width of selvage removed by said trimming means va ries directly with the thickness of the book.

4. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for advancing said books downstream to said trimming station; trimming means mounted on said trimming station and such that the edge from which the selvage is re moved is opposite a spine of said book; a sensor sensor so than the distance between said spine and the edge after removal of the selvuge of each book by said trimming means veries inversely with the thickness of the hook. 

1. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for advancing said books downstream to said trimming station; trimming means mounted on said trimming station and such that the edge from which the selvage is removed is opposite a spine of said book; a sensor mounted upstream of said trimming means and adapted to be resiliently biased into contact with one of said front page and said back page such that a change in the thickness of a book contacted by said sensor produces a corresponding change in the position of said sensor; and means operatively connected to said sensor and to said trimming means for detecting changes in the position of said sensor and for causing a resulting change in the position of said trimming means when said book is trimmed thereby so that the width of selvage removed by said trimming means varies directly with the thickness of the book.
 2. The machine as claimed in claim 1 wherein said detecting means comprises: a micro switch constituted by a post mounteD upstream of said trimming station; a first electrical terminal slideably mounted to said post and being normally spaced apart from and between a pair of spaced apart second and third electrically insulated terminals fixed to said post, said sensor being connected to and slideable with said first terminal such that a change of position of said sensor produces a corresponding movement of said first terminal into electrical contact with one of said pair of terminals; said machine further including memory means in circuit with said electrical terminals and with a prime mover for moving said trimming station; said memory means storing responses to book changes detected by said sensor and activating said prime mover to reflect said responses whereby the position of said trimming means is adjusted according to the thickness of book trimmed thereby.
 3. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for advancing said books downstream to said trimming station; trimming means mounted on said trimming station and positioned to remove selvage from an edge opposite a spine of each book; a sensor mounted to contact one of a front and back page of each said book such that a change in the thickness of a book contacted by said sensor produces a corresponding change in the position of said sensor; and means operatively connected to said sensor and to said trimming means for detecting changes in the position of said sensor and for causing a resulting change in the position of said trimming means when said book is trimmed thereby so that the width of selvage removed by said trimming means varies directly with the thickness of the book.
 4. A machine for trimming selvage from a plurality of books comprising: a trimming station; means for advancing said books downstream to said trimming station; trimming means mounted on said trimming station and such that the edge from which the selvage is removed is opposite a spine of said book; a sensor mounted to detect changes in the thickness of each said book; and means operatively connected to said sensor and to said trimming means for adjusting the relative position of said trimming means and said books in response to changes in book thickness detected by said sensor so that the distance between said spine and the edge after removal of the selvage of each book by said trimming means veries inversely with the thickness of the book. 